The systematic review of the “Notopithecinae” from the Casamayoran Age (middle Eocene), included in the Family Interatheriidae (Notoungulata), allowed clarifying the taxonomic and nomenclatural status of this group and other Paleogene notoungulates from Patagonia. This note proposes a new taxonomic interpretation of Acoelodus connectus, species described by Ameghino in the Family Acoelodidae, whose name was subsequently synonymized with the ?Henricosbornidae Paginula parca by Simpson. Both the holotype of Acoelodus connectus as others specimens attributed to this species and P. parca are herein recognized as Transpithecus obtentus, a casamayoran (Barrancan Subage) notopithecine from Patagonia.